// 文件系统服务实现

use log::info;
use crate::core::{Service, ServiceStatus};

/// 文件系统服务
pub struct FileSystemService {
    status: ServiceStatus,
}

impl FileSystemService {
    pub fn new() -> Result<Self, String> {
        Ok(FileSystemService {
            status: ServiceStatus::Stopped,
        })
    }

    /// 打开文件
    pub fn open_file(&self, path: &str, mode: FileMode) -> Result<FileHandle, String> {
        info!("Opening file: {} with mode {:?}", path, mode);
        // 这里实现文件打开逻辑
        Ok(FileHandle::new())
    }

    /// 读取文件
    pub fn read_file(&self, handle: &FileHandle, _buffer: &mut [u8]) -> Result<usize, String> {
        info!("Reading file: {}", handle);
        // 这里实现文件读取逻辑
        Ok(0)
    }

    /// 写入文件
    pub fn write_file(&self, handle: &FileHandle, data: &[u8]) -> Result<usize, String> {
        info!("Writing to file: {}", handle);
        // 这里实现文件写入逻辑
        Ok(data.len())
    }

    /// 关闭文件
    pub fn close_file(&self, handle: FileHandle) -> Result<(), String> {
        info!("Closing file: {}", handle);
        // 这里实现文件关闭逻辑
        Ok(())
    }

    /// 获取文件信息
    pub fn get_file_info(&self, _path: &str) -> Result<FileInfo, String> {
        // 这里实现获取文件信息逻辑
        Ok(FileInfo::default())
    }

    /// 列出目录内容
    pub fn list_directory(&self, _path: &str) -> Result<Vec<FileInfo>, String> {
        // 这里实现列出目录逻辑
        Ok(Vec::new())
    }
}

impl Service for FileSystemService {
    fn name(&self) -> &'static str {
        "filesystem"
    }

    fn start(&mut self) -> Result<(), String> {
        info!("Starting File System Service");
        self.status = ServiceStatus::Starting;
        
        // 这里可以添加文件系统服务启动逻辑
        // 例如：挂载文件系统、初始化缓存等
        
        self.status = ServiceStatus::Running;
        info!("File System Service started successfully");
        Ok(())
    }

    fn stop(&mut self) -> Result<(), String> {
        info!("Stopping File System Service");
        self.status = ServiceStatus::Stopping;
        
        // 这里可以添加文件系统服务停止逻辑
        // 例如：卸载文件系统、同步缓存等
        
        self.status = ServiceStatus::Stopped;
        info!("File System Service stopped successfully");
        Ok(())
    }

    fn status(&self) -> ServiceStatus {
        self.status.clone()
    }
}

/// 文件句柄
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct FileHandle(u64);

impl FileHandle {
    pub fn new() -> Self {
        static NEXT_ID: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(1);
        FileHandle(NEXT_ID.fetch_add(1, std::sync::atomic::Ordering::Relaxed))
    }
}

impl std::fmt::Display for FileHandle {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

/// 文件模式
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum FileMode {
    ReadOnly,
    WriteOnly,
    ReadWrite,
    Append,
}

/// 文件信息
#[derive(Debug, Clone)]
pub struct FileInfo {
    pub name: String,
    pub path: String,
    pub size: u64,
    pub file_type: FileType,
    pub permissions: FilePermissions,
    pub modified_time: std::time::SystemTime,
    pub created_time: std::time::SystemTime,
}

impl Default for FileInfo {
    fn default() -> Self {
        FileInfo {
            name: "unknown".to_string(),
            path: "unknown".to_string(),
            size: 0,
            file_type: FileType::Regular,
            permissions: FilePermissions::default(),
            modified_time: std::time::SystemTime::now(),
            created_time: std::time::SystemTime::now(),
        }
    }
}

/// 文件类型
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum FileType {
    Regular,
    Directory,
    SymbolicLink,
    Device,
    Other,
}

/// 文件权限
#[derive(Debug, Clone, Copy)]
pub struct FilePermissions {
    pub owner_read: bool,
    pub owner_write: bool,
    pub owner_execute: bool,
    pub group_read: bool,
    pub group_write: bool,
    pub group_execute: bool,
    pub others_read: bool,
    pub others_write: bool,
    pub others_execute: bool,
}

impl Default for FilePermissions {
    fn default() -> Self {
        FilePermissions {
            owner_read: true,
            owner_write: true,
            owner_execute: false,
            group_read: true,
            group_write: false,
            group_execute: false,
            others_read: true,
            others_write: false,
            others_execute: false,
        }
    }
}

/// 文件系统缓存
pub struct FileSystemCache {
    cache: std::collections::HashMap<String, Vec<u8>>,
    max_size: usize,
    current_size: usize,
}

impl FileSystemCache {
    pub fn new(max_size: usize) -> Self {
        FileSystemCache {
            cache: std::collections::HashMap::new(),
            max_size,
            current_size: 0,
        }
    }

    pub fn get(&self, path: &str) -> Option<&[u8]> {
        self.cache.get(path).map(|data| data.as_slice())
    }

    pub fn put(&mut self, path: String, data: Vec<u8>) -> bool {
        let data_size = data.len();
        if self.current_size + data_size > self.max_size {
            // 简单的LRU淘汰策略
            self.evict_oldest();
        }

        if self.current_size + data_size <= self.max_size {
            self.current_size += data_size;
            self.cache.insert(path, data);
            true
        } else {
            false
        }
    }

    fn evict_oldest(&mut self) {
        // 简单的淘汰策略：删除第一个元素
        if let Some((path, data)) = self.cache.iter().next() {
            let path = path.clone();
            let data_size = data.len();
            self.cache.remove(&path);
            self.current_size -= data_size;
        }
    }
}